Back Up, Restore, and Migrate Firefox
Bobbyd asked the Answer Line forum the best way to back up and restore Firefox bookmarks and settings.
With all its settings and add-ins, Firefox is a wonderfully configurable browser. Yet there's no obvious way to backup any of those configurations, or to move them to a new computer. There isn't even a clear way to save your bookmarks.
While there isn't a clear way, there is a reasonably easy one. You just have to know how. The trick is to back up one particular folder. I can't tell you the name of that folder, because the name is different on your computer than on mine, but I can tell you how to find it:
First, close Firefox. Doing this while the browser is running will be disastrous.
Once it's closed, select Start, then Run, type %appdata% (with the percentage signs) and press ENTER. Navigate the resulting Windows Explorer window to Mozilla\Firefox\Profiles (in other words, open the Mozilla folder inside your current location, then the Firefox folder inside that, and so on).
Now that you're in the Profiles folder, you'll see another folder with a random name and the extension .default--something like 4hw0enat.default. That's what you have to back up--that folder and all the files and folders inside it. Copy it to a safe location.
Here's how to restore it after you've bought a new PC or reinstalled Windows:
First, you'll have to install, run, and close Firefox on your new or newly setup PC. Then use the instructions above to find your new Firefox installation's Profiles folder. Copy your old .default folder from the backup into that new Profiles folder.
You'll now have two .default folders in Profiles. With the one you just copied selected, press F2to rename it, CTRL-C to copy the name, then ESC to not rename it, after all.
Move up the folder tree to the containing folder, which is called Firefox. Double-click the profiles.ini (Configuration Settings) file to open it in Notepad.
The last line of this file begins with Path=Profiles/. Select the rest of that line (everything to the right of the slash), and press CTRL-v to insert the name of your restored folder. Save the file, then open Firefox and everything should come up the way you want it.
Read the original forum discussion at http://forums.pcworld.com/message/245827.